Inversion Delivery Device And Method For A Prosthesis

ABSTRACT

A delivery device usable to deliver an inverting implant is provided that includes a positioning mechanism that automatically initiates the inversion process once a predetermined length of the implant has exited a delivery catheter. The positioning mechanism allows the implant to be safely and accurately deployed with reduced operator experience and in a greater variety of target locations.

RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/882,324 filed Oct. 13, 2015 entitled Inversion Delivery Device AndMethod For A Prosthesis, which claims benefit of and priority to U.S.Provisional Application Ser. No. 62/063,346 filed Oct. 13, 2014 entitledInversion Delivery Device And Method For A Prosthesis, both of which arehereby incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION

There has been a significant movement toward developing and performingcardiovascular surgeries using a percutaneous approach. Through the useof one or more catheters that are introduced through, for example, thefemoral artery, tools and devices can be delivered to a desired area inthe cardiovascular system to perform many number of complicatedprocedures that normally otherwise require an invasive surgicalprocedure. Such approaches greatly reduce the trauma endured by thepatient and can significantly reduce recovery periods. The percutaneousapproach is particularly attractive as an alternative to performingopen-heart surgery.

Valve replacement surgery provides one example of an area wherepercutaneous solutions are being developed. A number of diseases resultin a thickening, and subsequent immobility or reduced mobility, of heartvalve leaflets. Such immobility also may lead to a narrowing, orstenosis, of the passageway through the valve. The increased resistanceto blood flow that a stenosed valve presents can eventually lead toheart failure and ultimately death.

Treating valve stenosis or regurgitation has heretofore involvedcomplete removal of the existing native valve through an open-heartprocedure followed by the implantation of a prosthetic valve. Naturally,this is a heavily invasive procedure and inflicts great trauma on thebody leading usually to great discomfort and considerable recovery time.It is also a sophisticated procedure that requires great expertise andtalent to perform.

Historically, such valve replacement surgery has been performed usingtraditional open-heart surgery where the chest is opened, the heartstopped, the patient placed on cardiopulmonary bypass, the native valveexcised and the replacement valve attached. A proposed percutaneousvalve replacement alternative method on the other hand, is disclosed inU.S. Pat. No. 6,168,614 (the entire contents of which are herebyincorporated by reference) issued to Andersen et al. In this patent, theprosthetic valve is mounted on a stent that is collapsed to a size thatfits within a catheter. The catheter is then inserted into the patient'svasculature and moved so as to position the collapsed stent at thelocation of the native valve. A deployment mechanism is activated thatexpands the stent containing the replacement valve against the valvecusps. The expanded structure includes a stent configured to have avalve shape with valve leaflet supports begins to take on the functionof the native valve. As a result, a full valve replacement has beenachieved but at a significantly reduced physical impact to the patient.

However, this approach has decided shortcomings. One particular drawbackwith the percutaneous approach disclosed in the Andersen '614 patent isthe difficulty in preventing leakage around the perimeter of the newvalve after implantation. Since the tissue of the native valve remainswithin the lumen, there is a strong likelihood that the commissuraljunctions and fusion points of the valve tissue (as pushed apart andfixed by the stent) will make sealing around the prosthetic valvedifficult. In practice, this has often led to severe leakage of bloodaround the stent apparatus.

Other drawbacks of the Andersen '614 approach pertain to its reliance onstents as support scaffolding for the prosthetic valve. First, stentscan create emboli when they expand. Second, stents are typically noteffective at trapping the emboli they dislodge, either during or afterdeployment. Third, stents do not typically conform to the features ofthe native lumen in which they are placed, making a prosthetic valvehoused within a stent subject to paravalvular leakage. Fourth, stentsare subject to a tradeoff between strength and compressibility. Fifth,stents cannot be retrieved once deployed. Sixth, stents have an inherentstrength that is not adjustable.

As to the first drawback, stents usually fall into one of twocategories: self-expanding stents and balloon expandable stents.Self-expanding stents are compressed when loaded into a catheter andexpand to their original, non-compressed size when released from thecatheter. These are typically made of Nitinol. Balloon expandable stentsare loaded into a catheter in a compressed but relaxed state. These aretypically made from stainless steel or other malleable metals. A balloonis placed within the stent. Upon deployment, the catheter is retractedand the balloon inflated, thereby expanding the stent to a desired size.Both of these stent types exhibit significant force upon expansion. Theforce is usually strong enough to crack or deform thrombosis, therebycausing pieces of atherosclerotic plaque to dislodge and become emboli.If the stent is being implanted to treat a stenosed vessel, a certaindegree of such expansion is desirable. However, if the stent is merelybeing implanted to displace native valves, less force may be desirableto reduce the chance of creating emboli. An additional concern relatedto displacing an aortic valve is the risk of conduction disturbances(i.e. left bundle branch block) due to the close proximity of theconduction pathways to the native valve structure. Excessive radialforce applied at the native valve site increases the risk of irritationor damage to the conduction pathway and heart block.

As to the second drawback, if emboli are created, expanded stentsusually have members that are too spaced apart to be effective to trapany dislodged material. Often, secondary precautions must be takenincluding the use of nets and irrigation ports.

The third drawback is due to the relative inflexibility of stents.Stents typically rely on the elastic nature of the native vessel toconform around the stent. Stents used to open a restricted vessel do notrequire a seal between the vessel and the stent. However, when using astent to displace native valves and house a prosthetic valve, a sealbetween the stent and the vessel is necessary to prevent paravalvularleakage. Due to the non-conforming nature of stents, this seal is hardto achieve, especially when displacing stenosed valve leaflets.

The fourth drawback is the tradeoff between compressibility andstrength. Stents are made stronger or larger by manufacturing them withthicker members. Stronger stents are thus not as compressible as weakerstents. Most stents suitable for use in a valve are not compressibleenough to be placed in a thin catheter, such as a 18 Fr catheter. Largerdelivery catheters are more difficult to maneuver to a target area andalso result in more trauma to the patient.

The fifth drawback of stents is that they are not easily retrievable.Once deployed, a stent may not be recompressed and drawn back into thecatheter for repositioning due to the non-elastic deformation (stainlesssteel) or the radial force required to maintain the stent in place(Nitinol). Thus, if a physician is unsatisfied with the deployedlocation or orientation of a stent, there is little he or she can do tocorrect the problem.

The sixth drawback listed above is that stents have an inherent strengthand are thus not adjustable. As previously stated, stronger stents aremade with stronger members. Once a stent is selected and deployed, thereis little a physician can do if the stent proves to be too strong or tooweak.

Various embodiments of devices that solve these problems are introducedin U.S. Patent Publication No. 2006/0271166 to Thill et al., entitled“Stentless Support Structure,” the contents of which is incorporatedherein in their entirety. This publication teaches a braided mesh tubethat is capable of folding back and forth into itself to build, in situ,a support structure that is strong enough to hold back the leaflets of anative valve sufficiently to successfully deploy a replacement valve,thus obviating the need for excision of the native valve.Advantageously, because of the inverting nature of these devices, thebraided mesh, in an elongated delivery configuration, does not need topossess the strength to accomplish native valve displacement until theinversion process occurs. This allows the mesh tube to be constructedsuch that, in the elongated delivery state, the tube can be compressedinto a very small catheter, such as a 18 Fr or smaller catheter. Such asmall catheter significantly reduces patient trauma and allows for easypercutaneous, intraluminal navigation through the blood vessels. It isto be understood that terms like transluminal and percutaneous, as usedherein, are expressly defined as navigation to a target location throughand axially along the lumen of a blood vessel or blood vessels asopposed to surgically cutting the target vessel or heart open andinstalling the device manually. It is further to be understood that theterm “mesh” as used herein describes a material constructed of one ormore braided or woven strands.

In order to accomplish the folding back and forth feature of thisdevice, there are preformed, circumferential folds in the device. Oneembodiment has two circumferential folds that are longitudinally spacedapart in the extended configuration. One of these folds is preformed tofold inwardly, and the other is preformed to fold outwardly. Thesepreformed folds, when released out of a catheter, tend to return to afolded configuration that has a z-like cross-section. This cross-sectiondesign results not only because the inward pre-formed fold foldsinwardly and the outward pre-formed fold folds outwardly, but becausethese folds reverse longitudinal positions once folded. If the inwardpreformed fold is distal of the outward preformed fold in the extendedposition, in the folded position the inward preformed fold will beproximal of the outward preformed fold. This design allows a valve on adistal end of the device to be drawn into the device when folded,without requiring the valve itself to be inverted or everted. In oneembodiment having two preformed folds, the inversion process thusresults in a three-layered configuration that could be significantlyshorter than the extended length, depending on the spacing of the folds.

In the development of the devices described in the aforementionedpublication, U.S. Pat. Pub. 2006/0271166, it was found that,occasionally, it was advantageous to use an additional device to holdthe outermost layer of the implant axially in place while inversion of alayer was being effected. This gave rise to the delivery tool shown anddescribed in U.S. Patent Publication 2008/0082165 to Wilson et al.,entitled “Delivery Tool For Percutaneous Delivery Of A Prosthesis.” Thisdelivery tool includes an expandable mesh region that, when axiallycompressed, flares outwardly to form a bulbous or rounded structure ofincreased radius. Further axial compression creates a flat, disc-likesurface. In use, the device is extended through an implant prior toreleasing the implant from the delivery catheter. The device is thenexpanded to the disc-like configuration and pulled proximally to act asa backstop at a desired target location, against which the implant isdelivered. Thus, the disc-like device prevents axial migration of theimplant in a distal direction if and when distal force is placed on theimplant during inversion of the second or subsequent layers into thefirst layer.

It has been found, however, that in some cases, depending on targetlocation and patient anatomy, there is insufficient space in a distalaxial direction beyond the target location to efficiently use thisdelivery device. For example, some patients may have limited leftventricular space, which may prohibit the use of the backstop device.

There is thus a need for a device that is able to prevent axialmigration of the aforementioned braided implant devices duringinversion, but does not require significant space distally beyond thetarget location.

BRIEF SUMMARY OF THE INVENTION

The present invention meets the identified need by providing a deliverydevice that holds a braided implant in a desired location duringinversion of a subsequent layer into a first layer. More specifically,the present invention provides a delivery device that releasablyattaches at or near a first fold location, hereinafter referred to asthe “aortic flare,” which is a hinge point around which the inversion ofthe implant used with the present invention occurs.

Through attachment to the aortic flare, the delivery device of thepresent invention enables precise positioning and inversion by limitingadvancement of a portion of the implant while continuing to advance theremainder of the device. Hence, inversion is effected at a locationselected by the user, independent of patient anatomy or geometricinterference. One embodiment of the invention achieves this precisepositioning through attachment to a distal end of the device.

Two aspects of the present invention provide reliable performance of thedelivery device of the present invention. A first aspect is anattachment mechanism that can be mounted to a braided device withoutrequiring significant modification to the function of the braideddevice. This attachment mechanism provides device stabilization duringthe support structure inversion process. This attachment mechanismprovides both attachment to the device and a release capability in someembodiments. A second aspect of the present invention includespositioning mechanisms that prevent movement of the device in the targetlocation during the inversion process.

Another aspect of the present invention provides freedom of motion tothe support structure anchors as the device is being deployed, butautomatically actuates anchor locking mechanisms when the device hasbeen advanced to the appropriate position for the inversion process.This automatic actuation reduces the need for physician involvement orjudgment in the tensioning and setting of the anchor mechanisms. Thenature of the mechanism also accounts for manufacturing and usetolerances, precisely tuning the anchor locking mechanism to theselected valve and delivery system.

Yet another aspect of the invention provides a deployment device thatallows the positioning, implantation and deployment of a prostheticvalve such that the valve achieves complete function prior to releasingthe valve. The valve may be observed and verified that it is functioningnormally prior to release. If the valve is not functioning as intended,the entire device may be quickly pulled back into the delivery device.In some circumstances, the valve is able to be relocated and redeployed.

Still another aspect of the invention provides a delivery device thatincludes a limiter that may be set prior to or during the procedure. Thelimiter ensures that the braided implant does not exit the deliverydevice more than a desired amount, prior to inverting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of an embodiment of a deliverydevice of the present invention with an implant loaded in a distal endthereof;

FIG. 2a is a perspective view of a distal end of an embodiment of apusher catheter of the present invention;

FIG. 2b is a perspective view of a distal end of an alternativeembodiment to that of FIG. 2 a;

FIG. 3 is a perspective view of an embodiment of a distal end of arelease mechanism of the present invention in an open configuration;

FIG. 4 is a perspective view of the mechanism of FIG. 3 in a closedconfiguration;

FIG. 5 is a plan cross-sectional view of an embodiment of a deliverydevice of the present invention, just prior to an inversion process ofan implant;

FIG. 6 is a plan cross-sectional view of an embodiment of a deliverydevice as shown in FIG. 1, just after the implant has been inverted;

FIG. 7 is a perspective view of a pusher catheter of an embodiment of adelivery device;

FIG. 8 is a perspective view of a pusher catheter of an embodiment of adelivery device;

FIG. 9 is a perspective view of a pusher catheter of an embodiment of adelivery device;

FIG. 10 is a perspective view of a pusher catheter of an embodiment of adelivery device;

FIG. 11 is a plan view of an embodiment of a handle assembly of theinvention;

FIG. 12 is an exploded view of an embodiment of a valve retention cablecontrol of the invention;

FIG. 13 is a perspective view of an embodiment of a valve retentioncable control of the invention in a closed position;

FIG. 14 is a perspective view of an embodiment of a valve retentioncable control of the invention in an open position;

FIG. 15 is a partial perspective view of an embodiment of a handleassembly of the invention showing an embodiment of a pusher cathetercontrol;

FIG. 16 is a partial perspective view of an embodiment of a handleassembly of the invention showing an embodiment of a drive mechanism;

FIG. 17 is a perspective view of an embodiment of a tether releasecontroller of the invention in a closed position;

FIG. 18 is a perspective view of an embodiment of a tether releasecontroller of the invention in an open position;

FIG. 19 is an exploded view of an embodiment of a tether positioningmechanism of the invention;

FIG. 20 is a perspective view of an embodiment of a tether positioningmechanism of the invention in a locked position;

FIG. 21 is a perspective view of an embodiment of a tether positioningmechanism of the invention in an unlocked position;

FIG. 22 is a side view of an embodiment of a delivery device of thepresent invention in a vessel of a patient;

FIG. 23 is a side view of an embodiment of a delivery device as shown inFIG. 22, just after crossing a heart valve;

FIG. 24 is a side view of an embodiment of a delivery device as shown inFIG. 22, in which an implant is partially deployed;

FIG. 25 is a side view of an embodiment of a delivery device as shown inFIG. 22, in which the tethers are tightened;

FIG. 26 is a side view of an embodiment of a delivery device as shown inFIG. 22, just after the implant has been inverted;

FIG. 27 is a side view of an embodiment of a delivery device as shown inFIG. 22, just after releasing and withdrawing the tethers from theimplant;

FIG. 28 is a side view of an embodiment of a delivery device as shown inFIG. 22, just prior to releasing the attachment cables;

FIG. 29 is a side view of an embodiment of the implant, just afterrelease of the attachment cables;

FIG. 30 is a chart showing lead screw travel relative to handleposition;

FIG. 31 is an internal view of an embodiment of a tether tensioningsystem of the invention;

FIG. 32 is an perspective view of an embodiment of a tether tensioningsystem of the invention;

FIG. 33 is an internal view of an embodiment of a tether tensioningsystem of the invention;

FIG. 34 is an internal view of an embodiment of a tether tensioningsystem of the invention;

FIG. 35 is a perspective view of an embodiment of a tether tensioningsystem of the invention;

FIG. 36 is a plan view of an embodiment of a tether tensioning system ofthe invention;

FIG. 37 is a plan view of an embodiment of a tether tensioning system ofthe invention;

FIG. 38 is a plan view of an embodiment of a tether tensioning system ofthe invention;

FIG. 39 is a plan view of an embodiment of a tether tensioning system ofthe invention;

FIG. 40 is a plan view of an embodiment of a tether tensioning system ofthe invention;

FIG. 41 is a plan view of an embodiment of a tether tensioning system ofthe invention; and

FIG. 42 is a plan view of an embodiment of a tether tensioning system ofthe invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the Figures and first to FIG. 1, there is shown adistal end of a delivery device 10 of the present invention. Thedelivery device generally includes a delivery catheter 20, and a pushercatheter 30 slidably contained within the delivery catheter 20. Thepusher catheter 30 is preferably a multi-lumen catheter containinglumens for slidably containing and maintaining alignment of threeattachment cables 40 (hereinafter “valve retention cables”) (see FIG.3), each of which has a releasable grasping mechanism 50 at a distal endthereof. The delivery device 10 also includes at least one positioningmechanism 60 used to aid the tool or implant 1 in achieving a folded,deployed configuration from an extended, unfolded, navigationconfiguration. In one embodiment, the at least one positioning mechanism60 is attached to a distal end of the delivery catheter 20. In anotherembodiment, the at least one positioning mechanism 60 is slidablycontained within the delivery catheter 20, similar to the valveretention cables 40.

The delivery catheter 20 is an external sheath defining a single lumenfor housing the pusher catheter 30, the tool or implant 1, the valveretention cables 40, and the positioning mechanisms 60. The deliverycatheter 20, when loaded, houses a tool or implant 1 near its distal end22. The implant 1 is preferably an implant similar to those taught anddescribed in U.S. Patent Publication No. 2006/0271166. The deliverycatheter 20 may be formed with a preset curve at its distal end.Positive results have been achieved with a 180 degree preset curve.

The pusher catheter 30 may include up to seven lumens. Three lumensslidably house the three valve retention cables 40. In an embodimentused over-the-wire, a fourth lumen accommodates a guidewire. In yetanother embodiment, three additional lumens slidably house threepositioning mechanisms, described below.

FIGS. 2a and 2b show two similar embodiments of the pusher catheter 30of the present invention defining seven lumens. The pusher catheter 30includes a central guidewire lumen 32, and three lumens 34 that containeither the valve retention cables 40 or the positioning mechanismsdescribed below. The remaining three lumens 36 house the remaining valveretention cables or positioning mechanisms. In order to save on space,the lumens 36 may be formed as external indentations, thereby relying onthe inner wall of the delivery catheter 20 to complete the lumen andcontain the remaining valve retention cables or positioning mechanisms.In a preferred embodiment, the lumens 34 contain the valve retentioncables 40 and the lumens 36 contain the positioning mechanisms 60. Inthis embodiment, the pusher catheter 30 may continue to be advanced evenif the positioning mechanisms 60 can no longer be advanced.

In one embodiment, the positioning mechanisms are small enough to fitthree valve retention mechanisms, and an associated containment sheath,in a single lumen 36, leaving two other lumens 36 unused or availablefor use as irrigation channels.

The releasable grasping mechanisms 50 may be similar to those shown anddescribed in U.S. Pat. Pub. 2008/0082165 (at FIGS. 5-8). Anotherembodiment of releasable grasping mechanisms is shown in FIGS. 3 and 4.The grasping mechanisms 50 are attached to commissural points on animplant 1 when the device 10 is loaded. The grasping mechanism 50provide the ability to retract the implant back into the device 10 inthe event that the physician feels doing so is appropriate.

FIG. 3 shows a grasping mechanism 50 in an open configuration. Thegrasping mechanism 50 includes a hook 52 that slides within a mouth 54.The hook 52 defines a recess 56 sized to accommodate a component, suchas a commissural point or a braid, of the tool or implant 1. The mouth54 defines a slot 58 that is also sized to accommodate the component.FIG. 4 shows that when the grasping mechanism 50 is in a closedconfiguration, the recess 56 and the slot 58 together define a passage59 that traps the component therein.

The grasping mechanism 50 is attached to a distal end of an valveretention cable 40. The valve retention cable 40 includes a wire 42attached to the hook 52 and an elastomeric sheath 44 that is attached tothe mouth 54. The wire 42 and the hook 52 are slidably contained withinthe sheath 44 and the mouth 54. The sheath 44 is elastomeric such thatit is capable of being compressed longitudinally. This feature preventsaccidental release of a tool or component contained within the passage59. For example, when pulling a tool or implant back into the deliverysheath 20 during a retrieval, a load is placed on the wire 42, causingthe wire to stretch. If the sheath 44 were not compressed, the wire 42could stretch enough to cause the hook 52 to exit the mouth 54, therebyassuming the open configuration of FIG. 3. However, because the sheath44 is compressed when the hook 52 is drawn into the mouth 54 duringclosing, the sheath 44 elongates when the wire 42 is stretched, therebymaintaining the closed configuration of FIG. 4.

The positioning mechanisms 60 aid in inverting the tool or component 1.In one embodiment, shown in FIGS. 1, 5 and 6, the positioning mechanisms60 connect the the delivery catheter 20 with a first inversion pre-foldpoint (also referred to herein as an “aortic flare”) on the implant 1.

The positioning mechanisms 60 may comprise a plurality of tethers 62 andconnectors 64. The tethers 62 may be any resilient strand-like material,flexible enough to invert from a navigation configuration to adeployment configuration. In the navigation configuration, as shown inFIG. 1, the tethers extend proximally from the distal end of thedelivery catheter 20, to the connectors 64. In the deploymentconfiguration, shown in FIGS. 5 and 6, the tethers 62 extend distallyfrom the distal end of the delivery catheter 20 to the connectors 64. Inone embodiment, the connectors 64 are able to grasp any individual braidor strand of an implant 1. In another embodiment, the connectors 64 aredesigned to grasp the intersection of two braids or strands. In yetanother embodiment, the connectors 64 are able to grasp discreteattachment points (e.g. wire loops, sutures, etc.), that have beenintegrated into the mesh implant or tool 1. The length of the tethers 62are at least the length of the material of the implant 1 that extendsdistally of the connectors 64 when the implant 1 is loaded into thedelivery catheter 20. This way, the implant 1 remains completely withinthe delivery catheter 20 in the navigation configuration.

In another embodiment, the positioning mechanisms 60 are similar inconstruction to the valve retention cables 40 and releasable graspingmechanism 50. However, because the strength requirements of thepositioning mechanisms 60 are less than those of the valve retentioncables 40 and their releasable grasping mechanisms 50, the positioningmechanisms 60 may be smaller in diameter, thereby allowing a smalleroverall delivery device 10. Rather than being attached to the distal endof the delivery catheter 20, as described above, the positioningmechanisms 60 of this embodiment are slidably contained within thelumens 36 of the pusher catheter 30 shown in FIG. 2.

Referring to FIGS. 5 and 6, the device 10 is designed to be able to passover a guidewire 70 during navigation. A conical or otherwise tapereddilator tip 80 abuts against the distal end 22 of the delivery catheter20 and is flush therewith. The dilator 80 allows the device 10 to bepassed through the vasculature with minimal trauma. The dilator 80 isnot physically attached to the delivery catheter 20, such that it iseasily moved distally during delivery of the implant 1 to avoidinterference with the deployment of the implant 1.

Having described the various components of the present invention, thevarious steps and configurations that occur during navigation anddeployment of an implant can now be explained. FIG. 1 shows thenavigation configuration of the device 10. In the navigationconfiguration, the implant 1 is loaded into the distal end of thedelivery catheter 20 such that the implant 1 is in an elongated,non-folded state. The pusher catheter 30 is positioned within thedelivery catheter 20 with its distal end 22 proximal of the implant 1.The valve retention cables 40 extend distally from the pusher catheter30 and are connected to commissural points of the implant 1 with thereleasable grasping mechanisms 50. The conical dilator 80 abuts againstthe distal end 22 of the delivery catheter 20. During navigation, theentire device 10 and implant 1 travel over a guidewire 70 to the targetlocation.

FIG. 5 shows the initial stages of deployment of the implant 1. Thetarget location has been reached and the delivery catheter 20 isretracted while the pusher catheter 30 and valve retention cables (40)remain stationary relative to the target location. Retracting thedelivery catheter 20 causes the pusher catheter 30 to push the implant 1out of the distal end 22 of the delivery catheter. As the implant 1exits the delivery catheter 20 the implant 1 expands and the positioningmechanisms 60 are advanced through the delivery catheter 20 until thetethers 62 become taut, or in the case of the positioning mechanismsthat are slidably contained within the lumens of the pusher catheter 30,the positioning mechanisms 60 can no longer be advanced.

As seen in FIG. 6, further advancement of the pusher catheter 30 causesimplant material that is proximal of the connectors 64 to invert intothe implant material that is distal of the connector 64. This is becausethe positioning mechanisms 60 are taut and do not allow further distaladvancement of the implant 1. As such, the inversion of the implant 1 isurged by the preformed fold in the implant, the expansion of the memorymetal making up the implant 1, and the restraint provided by thepositioning mechanisms 60. Notably, the transition of the implant frominitial advancement to inversion happens automatically and is dictatedby the length of the tethers 64. As such, operator experience is notrequired to initiate inversion. Nor is there any reliance on anatomicalstructure to provide friction against the implant to initiate inversion.

Once the implant 1 has been fully deployed, the implant 1 is fullyfunctional prior to release. This allows verification of properoperation of the implant 1 via one or more imaging modalities prior tofull release of the implant 1. If proper operation is not achieved, thegrasping mechanisms 50 can be used to pull the implant 1 back into thedelivery catheter 20 such that the implant may be either removed orredeployed. If proper operation is verified, the connectors 64 areactuated to release the braids or strands of the implant 1. The pushercatheter 30 and the delivery catheter 20 are withdrawn slightly whilemaintaining connection with the implant 1 and the device 10 via thereleasable grasping mechanism. Subsequently, the grasping mechanisms 50are actuated to release the commissural points of the implant 1. Thepusher catheter 30 is retracted into the delivery catheter 20 and thedelivery catheter 20 and the guidewire 70 are withdrawn from thepatient.

FIGS. 7-21 illustrate another embodiment of a delivery device 100 thatis generally similar to the previously described delivery device 10,especially where noted with similar element numbers. However, thedelivery device 100 includes a positioning tether assembly 110, thedistal end of which is seen best in FIGS. 7-10, having a sliding releasemechanism for releasing a connection to the implant 1.

More specifically, the positioning tether assembly 110 includes aplurality of tethers 104 that are each arranged in a generally closedloop. These looped tethers 104 pass through portions of the implant 1and therefore can maintain the implant 1 in a desired position during aprocedure (e.g., can prevent distal movement of the implant 1). Thetethers can be disconnected from the implant 1 by releasing one end ofeach of the tethers 104, effectively opening the loop shape. In thisrespect, withdrawal of the positioning tether assembly 110 also pullsthe tethers 104 out of and away from the implant 1.

The release mechanism of the positioning tether assembly 110 istriggered by advancing a sliding member 114 to the position seen inFIGS. 8 and 10 from the retracted position seen in FIGS. 7 and 9. Notethat the tethers 104 are connected to a distal end 114B of the slidingmember 114 (e.g., either fixed in place or pass through the member 114back to the proximal end of the positioning tether assembly 110), butfor illustrative purposes are not shown as such in FIGS. 9 and 10.Initially, the free ends 104B of the tethers 104 are located within adepression 114A of the sliding member 114 and are captured by a firstslot 112A of an outer tether sheath 112. When the sliding member 114 isadvanced, the depression 114A is positioned beneath a wider, second slot112B, which allows the free ends 104B of the tethers 104 to be released.

As best seen in FIG. 9, the free ends 104B of the tethers 104 have agenerally larger size or diameter than the remaining portion of thetether 104 and can have a variety of different shapes, such as rounded,spherical or even square. The first slot 112A has a width that is largeenough to accommodate the diameter of the tether 104 but is smaller thanthe diameter of the free ends 104B, thereby allowing the tether 104 tolaterally slide within the slot 112A without the free ends 104B fromtraversing through.

The second slot 112B is positioned distal to the first slot 112A and hasa width that is larger than the free ends 104B. In this respect, oncethe depression 114A aligns under this second slot 112B, as seen in FIG.10, the free ends 104B are released, thereby allowing the tethers 104 toassume a generally linear configuration, similar to that in FIG. 8.

While two slots are shown, a single slot may alternately be used inanother embodiment. Specifically, the single slot may be similar in sizeto slot 112A, but extends to the distal end of the tether sheath 112. Inthis respect, the free ends 104B are released when the depression 114Ais advanced outside of the tether sheath 112.

The positioning tether assembly 110 may be constructed with an overalloutside diameter that is small enough to be slidingly contained in oneof the lumens 34 or 36 of the pusher catheter 30 shown in FIG. 2a or 2b.

FIGS. 11-22 show the proximal end or handle assembly 200 of the deliverydevice 100. The handle assembly generally includes valve retention cablecontrol group 210, a pusher catheter control 250, a drive mechanism 260,irrigation ports 280, and a tether control assembly 300.

The valve retention cable control group 210 includes a plurality ofvalve retention cable controls 212, housed in a recess 214 of the handle200, and a locking pin 216. The individual valve retention cablecontrols 212 are best seen in FIGS. 12-14.

FIG. 12 shows an exploded view of an individual valve retention cablecontrol 212. The control 212 includes a housing 218, to which isattached a proximal end of the elastomeric sheath 44 of the retentioncable 40 (see FIG. 3). Slidingly contained within the housing 218 is athumb slide 220, which is connected to the wire 42 of the retentioncable 40. Behind the thumb slide 220 is a spring-loaded catch 222. Inoperation, pulling the thumb slide rearward toward the catch 222 pullsthe wire 42 relative to the sheath 44, thereby retracting the hook 52into the mouth 54 at the distal end of the cable 40. The catch 222maintains the retention cable 40 in a closed position. The hook 52 canbe quickly released from the mouth 54 by depressing the catch 222.

FIG. 14 shows the thumb slide 220 in the forward, open position. Thecorresponding open position of the distal end of the cable 40 is alsoshown. FIG. 15 shows the thumb slide 220 in the rearward, closedposition. The corresponding closed position of the distal end of thecable 40 is also shown. Furthermore, a locking pin 216 has been insertedthrough the housing 218 and the thumb slide 220 to prevent accidentalrelease of the implant 1 held in the mouth 54 of the retention cable 40.

Referring back to FIG. 11, it is shown that there are three controls 212arranged in the handle 200. It can also be seen that a single lockingpin 216 passes through the handle 200 and all three controls 212. Thislocking pin 216 is a precautionary feature that ensures none of thecontrols 212 are inadvertently opened. Once the valve position andoperation have been verified, the physician is then able to unlock allthree controls 212 by removing the single pin 216.

FIG. 15 is a partial view of the handle 200 of the device 100. FIG. 15shows the pusher catheter control 250, which is shown as a sliding ring250 that slides over the handle 200. The ring 250 is connected through aslot 252 in the side of the handle 200 to the pusher catheter 30. Whenthe ring 250 is advanced to its most distal position, it may be rotatedto lock the pusher catheter relative to the valve retention cables 40.

The drive mechanism 260 is shown in FIG. 16. The drive mechanism 260includes a lead-screw 262 and a threaded nut combination 264. Thethreaded nut combination 264 includes a nut 266 contained within a knob268 and a quick release 270. Rotation of the knob 268 causes the nut 266to act against the lead-screw 262. The knob 268 is axially fixedrelative to the handle 200. The lead-screw 262 is slidingly containedwithin the handle 200. As such, when the nut 266 acts against thelead-screw 262, the lead-screw 262 advances or retracts in the handle200. The lead-screw 262 is connected at its distal end to the deliverycatheter 20. The rotatable threaded nut combination 264 thus allowsprecise control over the relative motion between the pusher catheter 30and the delivery catheter 20. The quick release 270 may be in the formof a button or lever that disengages the nut 266 from the threads of thelead-screw 262 to allow the pusher catheter 30 and valve retentioncables 40 to be quickly retracted into the delivery catheter 20.

It has been found that retracting an implant back jnto the deliverycatheter 20 is more successful when done quickly. A slow retractionincreases the risk that the catheter may buckle. As such, the handle 200has been designed to effect a quick retraction of an implant back intothe device 100 when necessary. This is accomplished by ensuring the ring250 is rotated into the locked position so that when the handle isretracted relative to the delivery catheter, the pusher catheter 30 andthe valve retention cables 40 are fixed relative to each other and thusretracted simultaneously. Depressing the quick release 270 while pullingon the knob 268 while holding the delivery catheter 20 stable causes theimplant to be quickly drawn back into the delivery catheter 20.

The various components of the tether control assembly 300 are shown inFIGS. 17-21. The tether control assembly 300 generally includes a tetherrelease controller 310 and a tether positioning mechanism 340.

The tether release controller 310 is shown in FIGS. 17 and 18 andincludes a housing 312 and a control knob 314. The housing 312 is fixedto the proximal end of the outer tether sheath 112 (See FIGS. 9 and 10)of the positioning tether assembly 110. The control knob 314 is able toslide axially, relative to the housing 312, and is attached to theproximal end of sliding member 114 (FIGS. 9 and 10). Thus, when thecontrol knob 314 is in the forward position shown in FIG. 18, thetethers are released. When the control knob 314 is in the rearwardposition shown in FIG. 17, the tethers ends are trapped in the firstslot 112A of the outer tether sheath 112. In the embodiment shown in theFigures, the control knob 314 can be turned in the closed position,thereby locking it closed. Also includes is a clip 320 which may be usedto prevent the control knob 314 from advancing to the open position inthe event it is accidentally actuated. The clip 320 is easily removedwhen it is desired to release the tethers.

FIGS. 19-21 show the tether positioning mechanism 340. The tetherpositioning mechanism is a slide-lock that includes a housing 342, alever 344, and a clamp block 346. The housing 342 passes over the outertether sheath 112 and keeps the tether sheath positioned between thelever 344 and the clamp block 346. When the lever 344 is lowered to theclosed position, shown in FIG. 20, the outer tether sheath 112, and thetethers contained therein, are clamped between the lever 344 and theblock 346, and cannot slide. Thus the tether positioning mechanism 340is fixed relative to the outer tether sheath 112. When the lever 344 isin the open position, the tether positioning mechanism 340 is able toslide over the outer tether sheath 112.

FIGS. 22-29 illustrate how the delivery device 100 can be used todeliver an implant 1 according to the present invention. First, animplant 1 is loaded into the delivery device 100. After the selectedvalve is rinsed, each of the three valve retention cables 40 areindividually attached to each of three wire form eyelets on the implant.This is accomplished by opening the valve retention cable control 212,pushing the thumb slide 220 forward to expose the hook 52 from the mouth54. The hook 52 is placed through the wire form eyelet and the thumbslide 220 is retracted rearwardly until it engaged the catch 222. Doingso locks the slide 220 and closes the hook 52 into the mouth 54. It alsocompresses the outer elastomeric sheath 44 of the valve retention cable40 to maintain interference between the hook 52 and the mouth 54, evenif a pulling force is placed on the cable sufficient to stretch thecable, thereby preventing accidental release during a retrievalprocedure.

After all three valve retention cables 40 are attached, the positiontethers 104 are attached to the implant 1. (Alternatively, the positiontethers 104 may be attached prior to the valve retention cables 40).This is accomplished by threading each of the three tethers 104 throughthe center of the implant and through a ventricular loop of theimplant's support structure at 120 degree intervals from the inside tothe outside of the implant. Once all three tethers 104 have beenthreaded, they are passed back up through the valve and the threetethers 104 are locked within the slot 112A of the outer tether sheath112. Locking is accomplished by pulling the control knob 314 androtating it to the locked position shown in FIG. 17.

Next the pusher catheter 30 is pushed forward to capture the valveretention cables 40. At the distal-most position of the pusher cathetercontrol ring 250, the ring 250 is rotated to lock the position of thepusher catheter 30 relative to the valve retention cables 40.

The implant 1 is now ready for loading into the delivery catheter 20.The delivery catheter 20 is advanced by rotating the drive knob 268toward the user, and the implant 1 is slowly drawn into the distal endof the delivery catheter 20. While the implant 1 is being loaded, theposition of the implant is noted so an observation can be made as towhen the implant has achieved the orientation in which the implant wouldbe exposed enough from the delivery catheter 20 to be able to invertinto itself. At this point the tether positioning mechanism 340, whichis in the unlocked position, is slid down the sheath 112 until itcontacts the delivery catheter manifold 282 (FIG. 11) and the lever 344is moved to the locked position.

Continued loading of the implant into the delivery catheter 20 causesthe tethers 104 and the tether sheath 112 to retract and the tetherpositioning mechanism 340 to move proximally relative to the deliverycatheter manifold 282. The implant is fully loaded when the dilator tip80 has been partially retracted into the delivery catheter 20 and thereis a smooth transition between the dilator tip and the delivery cathetertip.

As seen in FIG. 22, a guidewire 70 is placed across the native aorticvalve of the patient and extends out through the vascular introducer atthe femoral artery access site. The proximal end of the guidewire isinserted into the dilator tip 80 of the loaded delivery system and thesystem is advanced over the guidewire until the guidewire is visiblethrough the proximal end of the delivery system. The proximal end of theguidewire is then held stationary in order to maintain the position ofthe wire in the left ventricle of the patient and the delivery system isadvanced into the vasculature through the introducer and across thenative aortic valve 4 (seen best in FIG. 23). The guidewire passesthrough lumen 32 of the pusher catheter 30.

Turning to FIG. 24, the delivery sheath 20 is proximally retracted toexpose a portion of the implant 1 and the tethers 104. This isaccomplished by rotating the drive knob 268. As the implant 1 becomesexposed, it self-expands outward against the native valve 4. Duringdeployment, the operator maintains the implant position within thenative valve of the patient. If, however, the implant is pulled too highor pushed too low relative to the native valve, the implant can berecaptured by reversing the direction of the drive knob 268 rotation,which draws the implant back into the sheath 20 for repositioning.

As shown in FIG. 25, next, the implant 1 is folded or inverted on itselfby restraining the implant with the tethers 104 and pushing a proximalportion of the implant in a distal direction with the pusher catheter110. More specifically, when the first layer of the implant has beendeployed, the tether positioning mechanism 340 will have reached thedelivery catheter manifold. This freezes the position of the ventricularloops (the distal end) of the implant such that further advancement ofthe implant will result in a shortening and flaring of the implant inpreparation for valve invention.

This flaring aspect of the valve deployment has been described as theanchoring phase, as the implant has expanded to contact the native valvetissue and the aortic flare of the device provides substantialresistance to migration. Once the anchoring phase has begun, thedelivery catheter 20 is advanced through the access site and the patientvasculature. Doing so aligns the distal tip of the delivery cathetercoaxial to the native valve with the curve of the delivery catheter 20filling the outer curvature of the native aortic arch.

After the catheter 20 has been advanced, continued deployment of thevalve using the drive knob is used to produce implant invention. The actof inverting the implant also deploys the tissue valve component of theimplant. Once the implant has been inverted the valve begins tofunction, but that function is somewhat constrained due to the proximityof the tethers and the valve control cables.

After inversion has been accomplished, the user releases the tethers.First the tether positioning mechanism 340 is released by releasing thelever 344, separating it from the clamp block 346. The tetherpositioning mechanism 340 is free to float along the outer tether sheath112. The drive knob 268 is rotated to further back the delivery catheter20 away from the implant. Once the delivery catheter 20 is fullyretracted, the tethers 104 can be removed by rotating and releasing thetension in the control knob 314 of the tether release controller 310.Gently pulling on the tether release controller 310 will separate thetethers 104 from the implant.

Once the tethers 104 have been removed, only the valve retention cables40 remain connected to the implant 1, as seen in FIG. 28. As previouslydiscussed, these cables 40 are attached to a proximal feature on theimplant (e.g., the commissural points) and allow the physician tocompletely retract the implant 1 back into the delivery device 100 if aproblem arises during the delivery procedure. Specifically, in order toobserve full valve function without releasing the implant, the physicianbeings by rotating the ring 250 away from the operator and sliding thering 250 in a proximal direction, retracting the pusher catheter 30.With the pusher catheter 30 retracted, the prosthetic valve now beginsto function fully. The remaining attachment of the delivery system tothe implant via the valve retention cables 40 has little effect on thefunctionality of the implant.

Once satisfied, the physician next releases the implant by pulling thelocking pin 216 at the proximal end of the handle assembly 200. With thelocking pin 216 removed, each of the three valve retention cablecontrollers 212 can be sequentially released. This is accomplished bydepressing the catch 222 and sliding the thumb slide 220 forward,releasing the implant 1. Each cable can be individually retracted intothe delivery catheter after it has been disengaged. When all threecables are released, the valve is fully implanted and the deliverysystem may be removed from the vascular introducer of the patient.

Finally, the delivery device 100 and guidewire 70 is removed from thepatient, leaving only the functioning valve implant 1, as seen in FIG.29.

Repositioning and recapturing of the implant has been described and canbe seen as a significant advantage of the present system over otherdelivery systems on the market and being developed. The embodimentsdescribed above require manual steps which may be automated to a degreeby alternative embodiments now described.

For example, as mentioned previously, FIG. 5 shows the initial stages ofdeployment of the implant 1. The target location has been reached andthe delivery catheter 20 is retracted while the pusher catheter 30 andvalve retention cables 40 remain stationary relative to the targetlocation. Retracting the delivery catheter 20 causes the pusher catheter30 to push the implant 1 out of the distal end 22 of the deliverycatheter. As the implant 1 exits the delivery catheter 20 the implant 1expands and the positioning mechanisms 60 are advanced through thedelivery catheter 20 until the tethers 62 become taut.

Recall further that in FIG. 6, further advancement of the pushercatheter 30 causes implant material that is proximal of the connectors64 to invert into the implant material that is distal of the connector64. If repositioning of the implant is desired due to misplacement ofthe implant or suboptimal device orientation, the implant may berecaptured by reversing the rotation of the deployment dial, whichdrives a lead screw attached to the delivery catheter. However, if thepositioning mechanism has been engaged and tightened onto the device,this tightening must be reversed in order to provide slack for thedevice to fully elongate and be recaptured into the catheter. Ideally,this slack provided is sufficient to elongate the device, but notfurther such that the connectors extend substantially beyond the end ofthe implant or impinge on the nosecone as it is drawn into the deliverycatheter.

In one configuration, this slackening of the tension on the system maybe provided by manually holding the tether positioning mechanism forwardas the knob is rotated to recapture the implant. This maintains theforward position of the connectors as the valve is retracted.Importantly, the manual slackening of the connectors must be performedduring the initial recapture of the implant but must then be stopped asthe device is fully elongated to prevent over-extension of the tethersbeyond the end of the implant. This is achieved using visual cuesrelated to the appearance of the device via fluoroscopy to determinewhen slacking begins and ends.

A more automated embodiment allows this slackening of the tension isautomated such that the decision points as to initiation and terminationof slacking are controlled by the delivery system itself without inputfrom the system user. Predetermined set points in the system control theengagement and disengagement of the tether control assembly related tothe linear displacement of the device within the system.

FIG. 30 is a positioning chart that relates the lead screw travelrelative to the handle, thereby defining the displacements required forthe deployment, including unsheathing, inverting and expressing theimplant. The lead screw distances on the bottom axis of the chart areshown by way of an example that resulted positively for a given implantsize. Beginning at “Load”, the lead screw 262 is advanced distally(arrow 500), relative to the handle, a total of 5.5 inches to draw theimplant into the delivery catheter 20. Once loaded, the with an implantthe delivery catheter 20 is introduced into the patient and navigated tothe target site. Beginning at “Implant” on the chart, the lead screw 262is pulled proximally (arrow 502), to begin exposing the implant. Thechart indicates the first 3 inches of travel causes the implant to beunsheathed. If repositioning is necessary, as indicated by arrow 504,the lead screw direction may be reversed back to “implant.” The segment504 is the region in which the system may be actuated in forward orreverse directions when the tether control tension must be managed. Oncesatisfied with placement, at arrow 506 the lead screw continuesproximally an additional 2.5 inches, at which point the implant may bereleased (508) or, if observed valve function is unsatisfactory,retrieved at 510 by quickly advancing the lead screw 5.5 inches or moredistally.

FIG. 31 describes one embodiment of a system that automatically managesthe tension of the tether control system during the deployment andrepositioning of the device. A carriage 401 is attached to the proximalend of the tether control assembly and moves axially along with thecable. Engagement of the carriage 401 with the lead screw 408 isaccomplished through locking and unlocking of the follower arms 403.This locking and unlocking is managed by the follower arms 403travelling along the cam track 404.

When the implant is fully loaded within the delivery system, thefollower arms 403 are located at or near position 409 along the camtrack 404. As valve deployment is initiated, the follower arms 403 movealong the cam track 404 towards inflection point 405. During thismovement, the carriage 401 is engaged with the handle and the tethercontrol system travel simultaneously with the valve and no tension isapplied on the cables. When the follower arm 403 reaches the inflectionpoint 405 in the cam track 404, the follower arm is engaged with thecarriage 401 via the detent 406. In this way, the carriage 401 travelswith the lead screw 408 during subsequent device advancement, causingtension to be applied to the tether control system. This tensionincreases with increased travel along the cam track 404 towardsinflection point 407, ultimately resulting in valve inversion.

Inflection point 407 is designed to be reached by follower arms 403 atthe point that valve inversion has occurred. This inflection point 407causes the follower arms 403 to disengage with the detent 406 and allowthe tether control system to decouple from the lead screw 408 andreengage with the handle 402. This prevents over-tensioning of theimplant after device inversion and allows for further unsheathing of thesystem with the follower arms 403 travelling along cam track zone 410 toprovide for observation of full valve function while the system remainsattached to the valve.

Additionally, the cam track 404 may be designed with additionalinflection points and travel zones to allow for selective connection toother mechanisms within the handle. In particular, the follower arms 403may be designed to engage with the advance catheter hub 411 to retractthe advance catheter simultaneously with the delivery catheter upondevice inversion, simplifying the steps required to fully unsheathe thevalve.

A secondary benefit of engaging the advance catheter with the lead screwtravel relates to valve retrieval. The existing design requires that theadvance catheter be retracted to allow for full device function, andcritically must be manually re-advanced prior to a valve retrieval ifrequired. Integration of the advance catheter motion with the deliverycatheter removes the independent need for actuation and eliminates therisk that the advance catheter position is neglected during deviceretrieval.

Importantly, the position of carriage 401 must be maintained whiledisengaged from the follower arms 403 so that system registration ismaintained. One embodiment of this registration is demonstrated in FIG.32. A rigid plate 412 may be mounted within the handle 402 that containsplate detents 413. These detents 413 engage with ball spring plungers414 shown in FIG. 31 to lock the carriage to the plate 412.Disengagement of the carriage 401 from the handle 402 is achieved bydriving the lead screw 408 such that enough force is generated tocompress the ball spring plungers 414 and override the lockingmechanism. A second set of detents 413 are positioned at the proximalend of the plate 412 in order to reengage the carriage 401 at the end oftravel.

There are several alternative embodiments that provide the ability toselectively engage and disengage the carriage from the lead screw andhandle. In one embodiment, magnets are used in the place of the ballplunger and detent. FIG. 33 shows the position of the handle magnets 415and 416 and carriage magnet 417. Handle magnet 415 is used to engagewith carriage magnet 417 when the valve is loaded. When the lead screw408 drives the system such that the follower arms 403 are locked to thecarriage 401, further axial force will override the magnetic connectionand drive the carriage 401 proximally, applying tension to the tethercontrol system and causing valve inversion. When the follower arms 403reach the unlock position at inflection point 407, the follower arms 403are disengaged from the carriage 401 during further travel. At thispoint, the carriage magnet 417 has engaged with the handle magnet 416 tomaintain the carriage position.

Other versions of retention between the carriage and the handle havebeen envisioned. In yet another embodiment, a dual rack and pinionsystem may be used to selectively engage and disengage the carriage fromthe handle. FIGS. 34 through 42 demonstrate how independent racks may bemounted to the lead screw and the carriage, and offset pinions mountedwithin the handle. As the racks with their associated components travelthrough the handle, they engage with a lifter arm that is guided toengage the aligned pinions. By dropping off of one rack and pinion whenengaging with another rack and pinion, independent movement of thecomponents may be achieved.

More specifically, FIG. 34 shows an embodiment of a handle 600 having alead screw 602, a follower 604 with a rack 606, and a carriage 608 witha ball spring plunger 610. The rack 606 has teeth 612 only on aselective length thereof. The teeth 612 engage and disengage the rackwith a gear set 614 that is associated with the carriage 618 with acarriage rack 620.

As best shown in FIGS. 35-42, a pair of cam locks 630 and 632 ride adual cam lifter 634, which associate and disassociate the carriage andthe lead screw. In FIG. 36, the cam lock 632 is in the lower, engagedposition, thereby locking the carriage to the handle. In FIG. 37, thecam lock 632 is lifted by the dual cam lifter 634, unlocking thecarriage 608 so that it may move.

As the rack advances to the position shown in FIG. 38, the teeth 612engage the gears 614, causing the carriage 608 to move. In FIG. 39, thelead screw 602 and carriage 608 are shown moving together.

In FIG. 40, the dual cam lifter 634 has advanced to a position where itlifts the cam lock 630 so that it may be dropped into a détente 650, asshown in FIG. 42. Also, shown in FIG. 41, the partial teeth 606 reach aposition where they are no longer engaged with the gears 614. At thispoint the carriage 608 is once again locked with the handle.

An additional embodiment of this design involves attachment of thedistal conical tip 80 to the carriage 401. In this way, the tip 80 andthe associated guidewire lumen advance simultaneously with the deviceout of the delivery catheter during initial deployment, but the positionof the conical tip 80 relative to the handle 402 is maintained duringdevice inversion, preventing advancement of the conicall tip 80 into theleft ventricle during that inversion sequence. Additionally, if valveretrieval is required, the engagement of the conical tip 80 andassociated guidewire lumen with the carriage causes the conical tip 80to be advanced such that the conical tip 80 does not interfere withelongation and recapture of the device.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A method of acting on an implant during deliverycomprising: navigating an implant to a target delivery site using adelivery catheter, said implant being releasably connected to saiddelivery catheter by at least one tether; activating a mechanism thatalters a linear position of at least a first portion of said implantrelative to at least a second portion of said implant; wherein continuedactivation of said mechanism automatically engages and disengages acomponent attached to said at least one tether such that said tetherexperiences tension when said component is engaged and a release of saidtension when said component is disengaged, and such that said componentslides within a handle assembly for only a portion of a range of saidmechanism; and, wherein engagement and disengagement of said componentis dependent on a position of said mechanism.
 2. The method of claim 1wherein navigating an implant to a target delivery site using a deliverycatheter comprises navigating a prosthetic valve to the target deliverysite.
 3. The method of claim 1 wherein activating a mechanism thatalters a linear position of at least a first portion of said implantrelative to at least a second portion of said implant comprises rotatinga drive knob around a lead screw.
 4. The method of claim 3 whereincontinued activation of said mechanism comprises continued rotation ofthe drive knob in a single direction in order to cause the mechanism toengage and disengage the component attached to the at least one tether.5. The method of claim 1 wherein said engagement and disengagement ofsaid component is defined by positions of inflection points in a camtrack.
 6. The method of claim 1 said engagement and disengagement ofsaid component is defined by positions of magnets fixed linearlyrelative to said mechanism that interact with magnets that are fixedrelative to said component.
 7. The method of claim 1 wherein saidcomponent comprises a carriage.
 8. A medical implant delivery systemcomprising: an implant; a delivery catheter; at least one tether withinsaid delivery catheter and having a distal end and a proximal end, saiddistal end releasably attached to said implant; a carriage attached tosaid proximal end of said at least one tether; a handle assembly at aproximal end of said delivery catheter and slidably housing saidcarriage therein; an activation mechanism that changes a linear positionof first portion of said implant relative to at least a second portionof said implant; wherein operation of said activation mechanismautomatically engages and disengages said carriage such that saidcarriage slides within said handle assembly for only a portion of arange of said activation mechanism.
 9. The medical implant deliverysystem of claim 8 wherein said activation mechanism that changes alinear position of said first portion of said implant relative to atleast said second portion of said implant comprises a follower engagedto a lead screw, said follower including follower arms that ride in acam track, said cam track including inflection points that engage anddisengage said carriage.
 10. The medical implant delivery system ofclaim 8 wherein said activation mechanism that changes a linear positionof said implant relative to said delivery system comprises a followerengaged to a lead screw, said follower including magnets.
 11. Themedical implant delivery system of claim 8 wherein said activationmechanism that changes a linear position of said first portion of saidimplant relative to at least said second portion of said implantcomprises a follower engaged to a lead screw, said follower including arack with partial teeth that engage a gear set associated with acarriage rack on said carriage.
 12. The medical implant delivery systemof claim 11 further comprising a cam lifter on said rack that lifts andlowers at least one lock that connects said carriage to said lead screw.13. A medical implant delivery system comprising: an implant; a deliverycatheter; at least one tether within said delivery catheter and having adistal end and a proximal end, said distal end releasably attached tosaid implant; a pusher catheter slidingly disposed within said deliverycatheter; an inversion mechanism that selectively associates anddisassociates movement of said at least one tether with the relativemovement between the delivery catheter and the pusher catheter, saidinversion mechanism comprising: a carriage attached to said proximal endof said at least one tether; a handle assembly at a proximal end of saiddelivery catheter and slidably housing said carriage therein; anactivation mechanism that changes a linear position of a first portionof said implant relative to at least a second portion of said implant;wherein operation of said activation mechanism automatically engages anddisengages said carriage such that said carriage slides within saidhandle assembly for only a portion of a range of said activationmechanism.
 14. The medical implant delivery system of claim 13 whereinsaid first portion of said implant and said second portion of saidimplant fold into each other when moved relative to each other.
 15. Themedical implant delivery system of claim 13 wherein said at least onetether comprises three tethers.
 16. The medical implant delivery systemof claim 13 wherein said pusher catheter comprises a plurality oflumens.
 17. The medical implant delivery system of claim 13 wherein saidactivation mechanism comprises a lead screw.
 18. The medical implantdelivery system of claim 17 wherein said activation mechanism furthercomprises a follower that moves linearly when said lead screw isrotated.
 19. The medical implant delivery system of claim 18 whereinsaid follower comprises at least one follower arm.
 20. The medicalimplant delivery system of claim 19 wherein said at least one followerarm rides in a cam track that engages and disengages said at least onefollower arm with said carriage.